[Heathkit] Troubleshooting my HW-101

[Ted Bruce]

I'm resending this to the list; I can't figure out
when replies go to the author or to the list (maybe I
have to cc it).

Ken,
You and Glen have always been good for a wealth of
information; that's why I monitor this list.

On the 6146B issue, Bulletin HW-109 mentions
"reworked" GE tubes that may be marked 6146A or may
have 6146B etched in the glass.  Heathkit said those
are acceptable, and apparently aplied only to
Heathkit-supplied tubes.  Now, looking through one of
my printed bulletins list, I don't see any reference
to the GE-6146B being approved from some date going
forward.  It's on my main computer, I guess, which I
don't have access to right now during the move.  I'm
pretty sure I didn't make it up; I'm not that smart!

Thanks for the info on the additional checks, Ken, and
on the clarification of the Kenwood TS-rigs' finals
Glen.  My memory isn't what it used to be.

I'll put up another post to the list when I finish
this work.

73,
Ted
--- "Kenneth G. Gordon" <kgordon2006 at verizon.net>
wrote:

> On 22 Apr 2007 at 11:16, Ted Bruce wrote:
> 
> > Ken,
> > Thanks for the fine info.  My CW/Mic control has
> to be
> > fully clockwise on any band above 40m.
> 
> That isn't correct.
> 
> >  On 10m, I
> > don't even budge the ALC.  It's pegged low on that
> > band, and it may be due to the generic issue
> described
> > in one of the other bulletins.  I'll check and see
> if
> > I have a 6GH8, and if not, order a couple.
> 
> They are REALLY cheap. They were used a lot in TV
> sets. BTW, you 
> might want to check the 100 k resistor that feeds
> plate voltage to V-1. I 
> have found those open in the last two HW-101s I've
> worked on. If that 
> resistor is open, you will get some modulation, but
> not enough.
> 
> When you check plate and screen voltages for V-1
> don't be a bit 
> surprised by the fact that there is more screen
> voltage than plate 
> voltage: that is the way it is supposed to be.
> 
> Also, concerning ALC voltage: I have seen that vary
> all over the place, 
> depending on what tubes you have where and their
> condition.
> 
> According to the manual, the ALC voltage is supposed
> to be reading 
> between S-6 and S-9 on peaks normally, but that
> isn't necessarily so. 
> Use an external PEP wattmeter to check it all out. I
> am using an HM-
> 2140 here, properly calibrated. When everything is
> working properly, I 
> am getting about 130 watts PEP output, which is
> darned good. At that 
> point, the ALC voltage may or may not be reading S-6
> to S-9 on peaks, 
> depending on too many other variables to keep track
> off.
> 
> The ALC voltage is only a very poor indication of
> output, IMHO.
> 
> > 
> > The PA cage is marked "Use only 6146A", but I
> thought
> > that was resolved between Heathkit and GE after an
> > initial bad batch of 6146B tubes.
> 
> Not really. There were other issues involved, the
> main one being that 
> the interelectrode capactiances are pretty
> different. Also, the B and W 
> versions have higher plate dissipation ratings than
> the straight or A 
> versions.
> 
> I have gotten a set of NIB 6146Bs to work well in my
> HW-101, but I had 
> to "fiddle" with neutralization for a while to get
> it to become stable. I still 
> don't really trust them, but they have worked OK for
> the past year or 
> more.
> 
> >  It's my
> > understanding from the later bulletins that the
> newer
> > GE 6146B is the preferred tube.
> 
> I've got all those bulletings. I'll have to re-read
> them...
> 
> >  Also, I'm pretty sure
> > that the GE 6146W is a ruggedized 6146B.  I used a
> > pair for years in an SB-100.  I'll have to recheck
> > Glen's web site on the final scoop on that, as I
> know
> > he has a lot of info on the issue.
> 
> Yes. That is excellent info. Glen is a good fellow
> whom I have known for 
> a couple of years now.
> 
> Ken Gordon W7EKB

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